Use profiles to allow multiple people to use the same Firefox install on the same PC, but with their own personalisation, history, cookies, etc

All your Firefox settings, bookmarks, history, saved passwords and even add-ons are stored in a profile folder in your User directory. When you install Firefox for the first time, it automatically creates this as a new profile for storing all your data. Little known is the fact that Firefox can support multiple profiles and switch between them on launch.

In fact, any Firefox-based application (Thunderbird, SeaMonkey) supports multiple profiles and some of these tricks will work on them as well.

MASGAU supports some complex features – not apparent from its simple UI

Create multiple Firefox profiles

Hidden away behind a command line option is the ability to create and manage multiple Firefox profiles. Simply add the ”-P” command line parameter while launching Firefox, and you should see a dialog that lets you create new profiles, and delete / rename existing ones. If you’re running a 32-bit version of Windows your command line would be as follows:

C:\\Program Files\\Firefox\\firefox.exe -P

Each profile will have a separate history, set of bookmarks and add-ons even. If you’re using multiple versions of Firefox at the same time (Beta and Aurora) then it’s wise to create a separate profile for each.

If you uncheck the “Don’t ask at startup” option here, you’ll get this dialog each time you launch Firefox. If you want a create a different shortcut for each different version of Firefox, you can do that as follows:

C:\\Program Files\\Firefox\\firefox.exe --profile PROFILE_NAME

Changing the default version associated with a profile is quite simple. Now you can just double-click the profile name to launch it

Profiles are easy to back up. The backup process can take a while depending on the size of your profile

Run multiple versions of Firefox at the same time

While creating multiple profiles is useful, one of the best advantages of doing it is the ability to launch multiple distinct versions of Firefox at the same time.

If Firefox is already running, and you try to launch another Firefox instance with another profile by using the ”-P” option you’ll be surprised to find that Firefox will just open another window of the currently running Firefox. To successfully open a new version of

Firefox in a new instance, you need to add another command line option: ”—no-remote”. This makes the command line

as follows:

C:\\Program Files\\Firefox\\firefox.exe -P --no-remote

You can combine this with a profile name to launch multiple profiles or Firefox versions at once:

C:\\Program Files\\Aurora\\firefox.exe --profile aurora --no-remote

Use the Firefox ProfileManager app

A new enhanced version of the Firefox ProfileManager is being developed by Mozilla, and will eventually replace the built-in one.

The Firefox profile manager

This version can manage multiple version of Firefox, associate different profiles with different versions of Firefox, and can even be used to back up and restore profiles. It also supports an option to use a temporary throw-away profile for maximum privacy. Firefox ProfileManager will automatically detect if a version of Firefox is running and will launch a new version with the ”—no-remote” version automatically.